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Asian carp: Why this invasive species is so dangerous to the Great Lakes

Asian carp caught in St. Lawrence River
Asian carp caught in St. Lawrence River

In early June, two Quebec fishermen caught an Asian grass carp in the St. Lawrence River. This is sounding the alarm over the invasive species that experts say poses a serious threat to Canada’s Great Lakes.

There are several species of Asian carp: silver carp, bighead carp, grass carp and black carp. They were introduced to North America from China in the 1960s and 1970s in an effort to control algae, plants and snails in ponds. But since then, they have been spreading throughout waterways across North America.

READ MORE: 8 options to keep Asian carp out of Great Lakes: Army Corps report

They’re so pervasive and difficult to control that, according to Ontario’s Invading Species Awareness Program, it’s estimated that Asian carp “make up more than 50 per cent of the fish  by weight in the Illinois River.”

In parts of the Mississippi River, they’ve replaced some of the native species.

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The threat

Asian carp are a threat for several reasons and, unfortunately for Canada, our cooler waters provide them with a perfect spot to thrive.

WATCH: Invasive Asian carp species turns up in GTA waters

These fish are large: they can grow up to 25 cm in one year and up to a length of more than a metre. And they are voracious eaters. Asian carp can eat up to 20 per cent of their body weight in plankton a day. They can weigh up to 40 kilograms. On top of their incredible eating habits, they also reproduce very quickly.

According to Fisheries and Oceans Canada, Asian carp pose a threat on several levels.

When it comes to the silver carp, when startled by a passing boat engine, they can jump as high as three metres out of the water. As they can weigh as much as 40 kg, they can seriously injure boaters.

But a larger concern is the ecological threat to our waters.

Grass carp, like the one found by the Quebec fishermen earlier this month, consume vast amounts of aquatic plants. And, as they forage for food on lake bottoms, they can create murky water making it difficult for native species to find food. The destruction of the wetlands and aquatic vegetation can also make it difficult for young fishes to find cover from predators and can also disrupt spawning habitats.

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Because Asian carp breed so quickly, they can take over lake and river habitats, pushing out native species and unbalancing the natural ecosystem.

Asian carp also contain parasites not native to our waters, such as the Asian tapeworm.

Then there is the economic impact.

“The decline of native fish species could damage sport and commercial fishing in Ontario, which brings millions of dollars into the provincial economy each year,” said Sarah Chadwick, invasive species liaison at the Ontario Federation of Anglers and Hunters.

“Preventing them from spreading into the Great Lakes is the best way to prevent harm to Ontario’s native fish species.”

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In Ontario, it’s illegal to posses any Asian carp (as well as other invasive species of fish).

“Raising awareness about this is key and since 1992, the province has partnered with the Ontario Federation of Anglers and Hunters on programs including the Invading Species Awareness Program to fight invasive species,” Chadwick said.

There are efforts to combat Asian carp across North America. The Asian Carp Regional Coordinating Committee (ACRCC) was founded in the U.S. and works together with the Canadian government. Fisheries and Oceans Canada, the Ministry of Natural Resources and the Quebec ministère du Développement durable, de l’Environnement, de la Faune et des Parcs are all working together with ACRCC to spread awareness and prevent further spread of this invasive species that threaten our Great Lakes.

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